Featured Research

from universities, journals, and other organizations

Neurons In Zebrafish May Reveal Clues To The Wiring Of The Human Ear

Date:

October 15, 2008

Source:

Rockefeller University

Summary:

Developing neurons tend to play the field, making more connections than they will ever need. Then the weakest are cut. But scientists now show that neurons in young zebrafish -- vertebrates, like humans -- behave differently: They immediately find a cluster of specialized cells and make the right match. The findings may help reveal the mechanism by which analogous cells are wired in the human ear and eventually help those who are deaf or hard of hearing.

Share This

The right match. A zebrafish nerve fiber (red) descends toward a cluster of motion-detecting hair cells (green), synapsing only with those that detect water disturbances coming from the same direction.

Developing neurons tend to play the field, making more connections than they will ever need. Then the weakest are cut. But Rockefeller University scientists now show that neurons in young zebrafish — vertebrates, like humans — behave differently: They immediately find a cluster of specialized cells and make the right match. The findings may help reveal the mechanism by which analogous cells are wired in the human ear and eventually help those who are deaf or hard of hearing.

Related Articles

“These neurons seem to come out of nowhere and know exactly where to go,” says first author Aaron Nagiel, a biomedical fellow who works with A. James Hudspeth, head of the Laboratory of Sensory Neuroscience and an investigator at Howard Hughes Medical Institute. “The nerve fiber heads straight for its target, suggesting the brain takes a hardwired approach to assessing its surroundings.”

That target: hair cells, sensory cells with discrete bundles of hair-like projections called stereocilia, which increase in length from one edge of the hair bundle to the other. When deflected, the stereocilia can detect vanishingly small sounds or motions, and the direction in which the stereocilia are deflected determines the response of the hair cell. Nagiel and Hudspeth found that nerve fibers coming from the head only form connections with hair cells that detect stimuli coming from the same direction.

“The sister cells are mirror images of each other, and somehow they are able to advertise their different polarities,” says Nagiel. “The hair cells could be using a chemical cue to tell the neuron, ‘We are the right match.’”

Specifically, Nagiel and Hudspeth studied the zebrafish’s posterior lateral line system of cells whose hair-like projections are directly exposed to the water and sense its movement. The posterior lateral line, which runs horizontally from the zebrafish’s neck to its tail, is dotted with several clusters of hair cells called neuromasts, which are distributed in precise locations and contain up to 20 cells each. By using live imaging techniques with a confocal microscope and special dyes, the researchers found that nerve fibers form connections with many hair cells of the same polarity within one neuromast or several of them.

But that’s not all. Before now, Nagiel and Hudspeth had shown that neurons and hair cells make contact. ”But we wanted to rigorously show that these contacts were synapses,” says Nagiel. To do so, Nagiel and his colleagues constructed a molecule that enabled the team to look at the two cells’ point of contact underneath an electron microscope, a powerful camera that can image objects smaller than one-millionth of an inch.

“Once hair cells gather information from the environment, these synapses allow this information to be relayed to the brain,” says Nagiel. “That way, the zebrafish can respond accordingly.”

As for human medical therapies, several promising advances have emerged that can stimulate the growth of new hair cells in those who are deaf or hard of hearing. “Our work might eventually give us an idea of possible ways to make sure these hair cells get wired appropriately to the brain,” says Nagiel.

Rockefeller University. "Neurons In Zebrafish May Reveal Clues To The Wiring Of The Human Ear." ScienceDaily. ScienceDaily, 15 October 2008. <www.sciencedaily.com/releases/2008/10/081002211401.htm>.

Rockefeller University. (2008, October 15). Neurons In Zebrafish May Reveal Clues To The Wiring Of The Human Ear. ScienceDaily. Retrieved March 3, 2015 from www.sciencedaily.com/releases/2008/10/081002211401.htm

Rockefeller University. "Neurons In Zebrafish May Reveal Clues To The Wiring Of The Human Ear." ScienceDaily. www.sciencedaily.com/releases/2008/10/081002211401.htm (accessed March 3, 2015).

More From ScienceDaily

More Plants & Animals News

Featured Research

Mar. 3, 2015 — New assays can detect malaria parasites in human blood at very low levels and might be helpful in the campaign to eradicate malaria, reports a new study. An international team led by Ingrid Felger, ... full story

Mar. 3, 2015 — While studying a ground-nesting bird population near El Reno, Okla., a research team found that stress during a severe weather outbreak of May 31, 2013, had manifested itself into malformations in ... full story

Mar. 3, 2015 — The 3-D printing scene, a growing favorite of do-it-yourselfers, has spread to the study of plasma physics. With a series of experiments, researchers have found that 3-D printers can be an important ... full story

Mar. 3, 2015 — Most people consume more salt than they need and therefore have a higher risk of heart disease and stroke, which are the two leading causes of death worldwide. But a new study reveals that dietary ... full story

Mar. 3, 2015 — By examining the forces that the segments of mosquito legs generate against a water surface, researchers have unraveled the mechanical logic that allows the mosquitoes to walk on water, which may ... full story

Mar. 3, 2015 — Pediatric otolaryngologists and surgeons are concerned with parents getting the wrong message regarding the safety/desirability of letting babies and young children eat peanuts to prevent them from ... full story

Mar. 3, 2015 — Researchers have developed a new way of rapidly screening yeasts that could help produce more sustainable biofuels. The new technique could also be a boon in the search for new ways of deriving ... full story

Mar. 3, 2015 — Similar to humans and animals, plants possess an innate immune system that protects them from invading pathogens. Molecular structures that only occur in pathogens enable their recognition and ... full story

Mar. 3, 2015 — For almost a century, scientists have been puzzled by a process that is crucial to much of the life in Earth's oceans: Why does calcium carbonate, the tough material of seashells and corals, ... full story

Featured Videos

Rare Goblin Shark Found in Australia

AFP (Mar. 3, 2015) — A goblin shark, a rare sea creature described as an &apos;alien of the deep&apos; is found off Australia and delivered to the Australian Museum in Sydney. Duration: 01:25
Video provided by AFP

Zookeepers Copy Animal Poses In Hilarious Viral Photos

Buzz60 (Mar. 2, 2015) — Zookeepers at the Symbio Wildlife Park in Helensburgh, Australia decided to take some of their favorite animal photos and recreate them by posing just like the animals. Jen Markham (@jenmarkham) has the story.
Video provided by Buzz60

Related Stories

Feb. 6, 2015 — Lungfish and salamanders can hear, despite not having an outer ear or tympanic middle ear. These early terrestrial vertebrates were probably also able to hear 300 million years ago, as shown in a new ... full story

Feb. 18, 2014 — Using zebrafish, scientists can determine how individual neurons develop, mature and support basic functions like breathing, swallowing and jaw movement. Researchers say that learning about neuronal ... full story

June 24, 2013 — Myelin, the fatty coating that protects neurons, is destroyed in diseases such as multiple sclerosis. Researchers have been striving to determine whether oligodendrocytes, cells that produce myelin, ... full story

July 21, 2011 — Gardeners know that some trees require regular pruning: some of their branches have to be cut so that others can grow stronger. The same is true of the developing brain: cells called microglia prune ... full story

Mar. 18, 2011 — Scientists are exploring the molecules and tissues necessary for normal inner ear development in two different species that are model organisms for developmental biological studies: the African ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.